I liked some of season 5 but it felt a bit like it was the Amy Pond show with the added intro we got before the opening credits each episode with her voice over. But having watched the show over the years via box sets and such I found that for me series 8 and 9 were the ones I'd repeat the most.
I feel ever since series 5 the companions have taken a larger role and sometimes overshadowed the Doctor to a degree.
You've met Rose Tyler right? And Martha, and Donna...